CN113690127B - Wafer cleaning device and wafer cleaning method - Google Patents

Abstract

The present invention relates to the field of semiconductor manufacturing technology, and in particular, to a wafer cleaning apparatus and a wafer cleaning method. The wafer cleaning device includes: the brush head is used for brushing the surface to be cleaned of the wafer; the base is used for bearing the brush head, at least one conductive disc is arranged in the base, the disc surface of the conductive disc is parallel to the surface to be cleaned, and the base can rotate around the axis of the base; and the magnetic field generating structure is used for transmitting a magnetic field perpendicular to the disk surface direction of the conductive disk to the conductive disk, so that an induced electric field is generated in the conductive disk in the process of rotating the base. The invention reduces or even avoids the adsorption of the surface to be cleaned to the particles in the external environment, improves the cleaning quality of the wafer and improves the yield of the wafer product.

Description

Wafer cleaning device and wafer cleaning method

Technical field

The present invention relates to the field of semiconductor manufacturing technology, and in particular to a wafer cleaning device and a wafer cleaning method.

Background technique

During the semiconductor manufacturing process, due to van der Waals forces and electrostatic forces in various complex processes, a large number of dust particles, metal ions, organic matter, etc. will be adsorbed on the back of the wafer, resulting in the generation of wafer defects, thus seriously affecting The yield and yield of the final semiconductor device produced.

In order to solve this problem, the current main method for wafer back surface treatment (BST) is to use a combination of brush scrubbing and deionized water spraying. However, on the one hand, most existing brushes are made of materials with poor conductivity. In this way, when the brush is scrubbing the back of the wafer, the friction with the back of the wafer will cause the accumulation of static electricity. It will adsorb particulate matter in the environment to the back of the wafer or the back of the chuck used to carry the wafer; on the other hand, the conductivity of deionized water is very low, and the spraying of deionized water is not good for the wafer. Release of static charge on the backside.

Therefore, how to avoid adsorbing particulate matter during the cleaning process of the back side of the wafer, thereby improving the yield of wafer products, is an urgent technical problem that needs to be solved.

Contents of the invention

The present invention provides a wafer cleaning device and a wafer cleaning method, which are used to solve the problem in the prior art that particle adsorption is easily caused during the cleaning process of the back side of the wafer, so as to improve the yield of wafer products.

In order to solve the above problems, the present invention provides a wafer cleaning device, including:

Brush head, used to scrub the surface of the wafer to be cleaned;

A base for carrying the brush head, the base has at least one conductive disk, the surface of the conductive disk is parallel to the surface to be cleaned, and the base can rotate around its axis;

A magnetic field generating structure is used to emit a magnetic field perpendicular to the surface direction of the conductive disk to the conductive disk, so that an induced electric field is generated in the conductive disk during the rotation of the base.

Optionally, the number of the conductive disk is one, and the axis of the conductive disk coincides with the axis of the base.

Optionally, the number of the conductive disks is multiple, and the plurality of conductive disks are symmetrically distributed about the axis of the base.

Optionally, the shape of the conductive disk is a sector, and a plurality of the conductive disks are in contact with each other to form a disk shape.

Optionally, in a direction perpendicular to the base, the projection of the conductive disk is at least partially located on the periphery of the projection of the brush head.

Optionally, the conductive disk is embedded inside the base; or

The conductive disc is located on the surface of the base facing the brush head.

Optional, also includes:

A controller, connected to the base and the magnetic field generating structure, used to adjust one or both of the rotational speed of the base, the rotation direction of the base, the direction of the magnetic field, and the intensity of the magnetic field. above.

Optionally, the brush head is a conductive brush head.

In order to solve the above problems, the present invention also provides a wafer cleaning method, which includes the following steps:

Provide a wafer cleaning device as described in any one of the above;

While the brush head is scrubbing the surface to be cleaned, the base is driven to rotate around its axis and the magnetic field generating structure is driven to emit the magnetic field. During the rotation of the base, the conductive An induced electric field is generated in the disk.

Optional, also include the following steps:

Adjust one or more of the rotational speed of the base, the rotation direction of the base, the direction of the magnetic field, and the intensity of the magnetic field to change the magnitude and/or direction of the induced electric field.

In the wafer cleaning device and wafer cleaning method provided by the present invention, a conductive disk is provided in a base for carrying a brush head, and the rotation of the base is used to drive the rotation of the conductive disk, so that the conductive disk can cut A magnetic field perpendicular to the surface of the conductive disk forms a potential difference between the center and edge of the conductive disk, generating an induced electric field, and using the induced electric field to absorb electrostatic charges on the surface of the wafer to be cleaned , thereby reducing or even avoiding the adsorption of particulate matter in the external environment by the surface to be cleaned, improving the quality of wafer cleaning, and increasing the yield of wafer products.

Description of the drawings

Figure 1 is a schematic structural diagram of a wafer cleaning device in a specific embodiment of the present invention;

Figure 2 is a schematic structural diagram of a conductive disk in a specific embodiment of the present invention;

Figure 3 is another structural schematic diagram of a conductive disk in a specific embodiment of the present invention;

Figure 4 is a flow chart of a wafer cleaning method in a specific embodiment of the present invention.

Detailed ways

The specific embodiments of the wafer cleaning device and the wafer cleaning method provided by the present invention will be described in detail below with reference to the accompanying drawings.

This specific embodiment provides a wafer cleaning device. Figure 1 is a schematic structural diagram of the wafer cleaning device in the specific embodiment of the present invention. As shown in Figure 1, the wafer cleaning device described in this specific embodiment includes:

The brush head is used for brushing the surface to be cleaned of the wafer 10;

The base 11 is used to carry the brush head. The base 11 has at least one conductive disk 13. The surface of the conductive disk 13 is parallel to the surface to be cleaned, and the base 11 can rotate around its axis. rotation;

The magnetic field generating structure is used to emit a magnetic field perpendicular to the surface direction of the conductive disk 13 to the conductive disk 13, so that an induced electric field is generated in the conductive disk 13 during the rotation of the base 11.

Specifically, the wafer 10 may be a single crystal wafer or a wafer with a device structure formed on the surface. Whether it is a single crystal wafer or a wafer with a device structure formed on the surface, the wafer 10 includes a front side for forming the device structure and a back side opposite to the front side. In this specific embodiment, the back surface of the wafer 10 is used as the surface to be cleaned. The brush head includes a brushing part 122 for contacting the surface to be cleaned of the wafer 10 , and a connecting part 121 connecting the brushing part 122 and the base 11 . During the process of the wafer cleaning device cleaning the surface to be cleaned of the wafer 10 , the base 11 rotates around its axis (for example, clockwise rotation or counterclockwise rotation), and the base 11 The rotation of the brush head drives the rotation of the brush head located thereon, so that the brushing part 122 rubs and scrubs the surface to be cleaned of the wafer 10 to remove residual contaminants on the surface to be cleaned.

The direction of the dotted arrow in Figure 1 indicates the direction of the magnetic field. In this specific embodiment, by arranging the conductive disk 13 in the base 11 , the base 11 can also drive the conductive disk 13 to rotate while the base 11 rotates. The magnetic field generating structure emits a magnetic field perpendicular to the surface direction of the conductive disk 13 to the conductive disk 13. For example, in FIG. 1, the plane where the surface of the conductive disk 13 is located is the XY plane. The magnetic field generates The direction of the magnetic field emitted by the structure is the Z-axis direction.

This specific embodiment will be described by taking the direction of the magnetic field along the negative direction of the Z-axis (that is, vertically downward) and the rotation direction of the base 11 as a clockwise direction as an example. When the base 11 rotates in the clockwise direction, the conductive disk 13 is driven to rotate in the clockwise direction. The rotating conductive disk 13 cuts the magnetic field lines of the magnetic field, causing positive charges to accumulate at the edge of the conductive disk 13 (that is, forming a high potential at the edge), and negative charges to accumulate at the center of the conductive disk 13 (that is, a low potential is formed at the center portion), thereby generating a potential difference between the edge portion and the center portion of the conductive disk 13 to form an induced electric field. After the induced electric field is formed, the electrostatic charge 14 located on the surface to be cleaned can be adsorbed, so that the electrostatic charge 14 accumulated on the surface to be cleaned moves toward the high potential area or low potential on the conductive disk 13 The area moves away from the surface of the wafer 10, thereby reducing the static charge 14 on the surface to be cleaned, preventing the wafer 10 from adsorbing particulate matter in the external environment during the cleaning process, and improving the quality of wafer cleaning. , improving the yield of wafer products. The above is just an example. Those skilled in the art can also set the direction of the magnetic field to the positive direction of the Z axis (that is, vertically upward) according to actual needs, and the rotation direction of the base 11 can also be counterclockwise.

In this specific embodiment, the material of the conductive disk 13 can be an organic conductive material or a metal material, and those skilled in the art can choose according to actual needs.

Optionally, the number of the conductive disk 13 is one, and the axis of the conductive disk 13 coincides with the axis of the base 11 .

Figure 2 is a schematic structural diagram of a conductive disk in a specific embodiment of the present invention. Specifically, the number of the conductive disk 13 may be only one, and the shape of one conductive disk 13 may be a circle, an ellipse, or any polygon. FIG. 2 shows a schematic diagram when the shape of the conductive disk 13 is circular. The dotted arrows in FIG. 2 represent the direction of the magnetic field, and the solid arrows represent the rotation direction of the conductive disk 13 . The axis of the conductive disk 13 coincides with the axis of the base 11 , that is, the projection of the center of the conductive disk 13 coincides with the projection of the center of the base 11 . In this way, during the rotation of the base 11 , the conductive disk 13 also rotates around the axis of the base 11 . In order for the conductive disk 13 to absorb as much electrostatic charge 14 on the surface to be cleaned as possible, the area of the conductive disk 13 facing the wafer 10 may be equal to the direction of the base 11 along the disk surface. cross-sectional area. Those skilled in the art can adjust the shape and/or size of the conductive disk 13 according to actual needs.

Optionally, the number of the conductive disks 13 is multiple, and the plurality of conductive disks 13 are symmetrically distributed about the axis of the base 11 .

Optionally, the conductive disk 13 is in a sector shape, and a plurality of the conductive disks 13 are in contact with each other to form a disk shape.

Figure 3 is another structural schematic diagram of a conductive disk in a specific embodiment of the present invention. Figure 3 shows a schematic diagram when the shape of the conductive disks 13 is a sector and the number of the conductive disks 13 is eight. The dotted arrows in Figure 3 represent the direction of the magnetic field, and the solid arrows represent the direction of the conductive disks 13. direction of rotation. When the number of the conductive disks 13 is multiple, the plurality of conductive disks 13 can be symmetrically distributed around the axis of the base 11 so that the plurality of conductive disks 13 are combined into a circle or ellipse by contacting each other. shape or any polygon, and the axis of the combined figure coincides with the axis of the base 11 .

Figure 3 is an example of a plurality of the sector-shaped conductive disks 13 forming a circular shape by contacting each other at the center of the circle. Those skilled in the art can also adjust the shape and/or size of the conductive disks 13 according to actual needs, so that The plurality of conductive disks 13 contact each other to form a circular ring shape. This specific embodiment does not limit the shape of the combination of the plurality of conductive disks 13 .

Optionally, in a direction perpendicular to the base 11 , the projection of the conductive disk 13 is at least partially located on the periphery of the projection of the brush head.

Specifically, in order to fully move the electrostatic charge 14 on the surface to be cleaned of the wafer 10 toward the base 11 , thereby reducing the residual electrostatic charge 14 on the surface to be cleaned as much as possible, The projection of the electrically conductive disc 13 is located at least partially on the periphery of the projection of the brush head. For example, multiple brush heads can be connected to the surface of the base 11 at the same time, and the projection of the conductive disk 13 can be located and only between two adjacent brush heads; or, along a vertical direction In the direction of the base 11, the projection of the conductive disk 13 covers the projection of the brush head and extends to the outside of the projection of the brush head. The plurality mentioned in this specific embodiment refers to two or more.

Optionally, the conductive disk 13 is embedded inside the base 11; or

The conductive disk 13 is located on the surface of the base 11 facing the brush head.

Specifically, those skilled in the art can adjust the specific position of the conductive disk 13 in the base 11 according to actual needs. For example, embedding the conductive disk 13 inside the base 11 can avoid damage to the conductive disk 13 by chemical cleaning agents or deionized water during cleaning of the wafer 10; The conductive disk 13 is located on the surface of the base 11 facing the brush head, so that the shape, size or material of the conductive disk 13 can be adjusted according to actual needs.

Optionally, the wafer cleaning device also includes:

A controller, connected to the base and the magnetic field generating structure, used to adjust one of the rotation speed of the base 11, the rotation direction of the base 11, the direction of the magnetic field, the intensity of the magnetic field, or Two or more.

Specifically, the conductive disk 13 generates an induced electric field by cutting the magnetic field lines, and the intensity of the generated induced electric field depends on the intensity of the magnetic field emitted by the magnetic field generating structure and the rotation speed of the conductive disk 13, The direction of the induced electric field depends on the direction of the magnetic field and the rotation direction of the conductive disk 13; and the force of the induced electric field on the electrostatic charge 14 on the surface to be cleaned of the wafer 10 depends on The direction of the force depends on the direction of the induced electric field and the charge amount of the electrostatic charge 14 . Therefore, by adjusting one or more of the rotation speed of the base 11 , the rotation direction of the base 11 , the direction of the magnetic field, and the intensity of the magnetic field, the size and/or the magnitude of the induced electric field can be adjusted. direction, thereby adjusting the force magnitude and force direction of the electrostatic charge 14 on the surface of the wafer 10, thereby improving the flexibility of use of the wafer cleaning device.

Optionally, the brush head is a conductive brush head.

Specifically, in order to reduce the accumulation of electrostatic charge 14 generated by the brush head during friction brushing of the surface to be cleaned of the wafer 10, the conductivity of the brushing portion 122 of the brush head can be enhanced, For example, the brushing portion 122 is formed of conductive material.

For example, the material of the brushing part 122 is graphene oxide (GO) or a blend copolymer of carbon nanotubes (CNT) and polyvinyl alcohol (PVA). Polyvinyl alcohol has poor electrical conductivity, but blended copolymers of graphene oxide or carbon nanotubes and polyvinyl alcohol have better electrical conductivity. This is because graphene oxide or carbon nanotubes contain a large number of hydroxyl groups (-OH) and carboxyl groups (-COOH), while polyvinyl alcohol has hydroxyl groups. Therefore, when the graphene oxide or carbon nanotubes are combined with poly(vinyl alcohol), During the blending and copolymerization of vinyl alcohol, the hydroxyl groups and carboxyl groups in graphene oxide or carbon nanotubes will have strong hydrogen bonds with the hydroxyl groups in polyvinyl alcohol. Graphene oxide or carbon nanotubes and polyvinyl alcohol have good properties. Compatibility, graphene oxide or carbon nanotubes can be fully dispersed in the polyvinyl alcohol matrix, thereby improving the conductivity of polyvinyl alcohol.

The method for blending copolymers of graphene oxide or carbon nanotubes and polyvinyl alcohol can be as follows: first, dissolve graphene oxide or carbon nanotubes in deionized water, distribute them evenly through ultrasonic vibration, and then add dimethyl sulfoxide (DMSO) and polyvinyl alcohol resin, and stir at room temperature for 1 hour to mix evenly. Wherein, the volume ratio of the deionized water to the dimethyl sulfoxide is 3:7. The mass ratio of graphene oxide or carbon nanotubes to polyvinyl alcohol is 0.05% to 0.25%. After that, the uniformly mixed mixed solution was heated up to 110°C under pressure and dissolved. Finally, after vacuuming to 0.1MPa to 0.01MPa, the dissolved solution is injected into the mold for deaeration molding to form the brushing part 122 . The above are only examples, and those skilled in the art can adjust the process flow and process parameters according to actual needs.

Not only that, this specific embodiment also provides a wafer cleaning method. Figure 4 is a flow chart of a wafer cleaning method in a specific embodiment of the present invention. The wafer cleaning method provided in this specific embodiment can be implemented using a wafer cleaning device as shown in Figures 1-3. As shown in Figures 1-4, the wafer cleaning method provided by this specific embodiment includes the following steps:

Step S41, provide a wafer cleaning device as described in any one of the above;

Step S42: While the brush head is scrubbing the surface to be cleaned, the base 11 is driven to rotate around its axis and the magnetic field generating structure is driven to emit the magnetic field at the same time. During the rotation of the base 11 An induced electric field is generated in the conductive disk 13 .

Optionally, the wafer cleaning method further includes the following steps:

Adjust one or more of the rotation speed of the base 11 , the rotation direction of the base 11 , the direction of the magnetic field, and the intensity of the magnetic field to change the magnitude and/or direction of the induced electric field.

The wafer cleaning device and the wafer cleaning method provided by this embodiment provide a conductive disk in a base for carrying the brush head, and use the rotation of the base to drive the rotation of the conductive disk, so that the conductive disk A magnetic field perpendicular to the surface of the conductive disk can be cut, thereby forming a potential difference between the center and the edge of the conductive disk, generating an induced electric field, and using the induced electric field to absorb the particles on the surface to be cleaned of the wafer. Static charges are thereby reduced or even avoided from adsorption of particulate matter in the external environment by the surface to be cleaned, thereby improving the quality of wafer cleaning and increasing the yield of wafer products.

The above are only preferred embodiments of the present invention. It should be noted that those of ordinary skill in the art can also make several improvements and modifications without departing from the principles of the present invention. These improvements and modifications should also be regarded as It is the protection scope of the present invention.

Claims (10)

1. A wafer cleaning apparatus, comprising:

the brush head is used for brushing the surface to be cleaned of the wafer;

the base is used for bearing the brush head, at least one conductive disc is arranged in the base, the disc surface of the conductive disc is parallel to the surface to be cleaned, and the base can rotate around the axis of the base;

a magnetic field generating structure for emitting a magnetic field perpendicular to a disk surface direction of the conductive disk to the conductive disk so that an induced electric field is generated in the conductive disk during rotation of the base;

when the brush head brushes the surface to be cleaned, the base is driven to rotate around the axis of the base, and the magnetic field generating structure is driven to emit the magnetic field, an induction electric field is generated in the conductive disc in the process of rotating the base, and the induction electric field can absorb electrostatic charges on the surface to be cleaned of the wafer.

2. The wafer cleaning apparatus of claim 1, wherein the number of conductive pads is one and an axis of the conductive pads coincides with an axis of the susceptor.

3. The wafer cleaning apparatus of claim 1, wherein the number of conductive pads is a plurality, and wherein the plurality of conductive pads are symmetrically distributed about an axis of the susceptor.

4. The wafer cleaning apparatus of claim 3, wherein the conductive plate has a fan shape, and a plurality of the conductive plates are in contact with each other to form a disk shape.

5. A wafer cleaning apparatus according to claim 2 or claim 3, wherein the projection of the conductive pad is located at least partially around the periphery of the projection of the brush head in a direction perpendicular to the base.

6. The wafer cleaning apparatus of claim 1, wherein the conductive plate is embedded inside the base; or alternatively

The conductive disc is positioned on the surface of the base facing the brush head.

7. The wafer cleaning apparatus of claim 1, further comprising:

and the controller is connected with the base and the magnetic field generating structure and is used for adjusting one or more than two of the rotating speed of the base, the rotating direction of the base, the direction of the magnetic field and the strength of the magnetic field.

8. The wafer cleaning apparatus of claim 1, wherein the brush head is a conductive brush head.

9. The wafer cleaning method is characterized by comprising the following steps of:

providing a wafer cleaning apparatus according to any one of claims 1-8;

and when the brush head brushes the surface to be cleaned, the base is driven to rotate around the axis of the base, and the magnetic field generating structure is driven to emit the magnetic field, so that an induced electric field is generated in the conductive disc in the process of rotating the base.

10. The wafer cleaning method of claim 9, further comprising the steps of:

and adjusting one or more than two of the rotating speed of the base, the rotating direction of the base, the direction of the magnetic field and the strength of the magnetic field, and changing the size and/or the direction of the induced electric field.